Variable-displacement pump



July 2, 1929. H. ERNST VARIABLE DISPLACEMENT PUMP 3 Sheets-Sheet 1 Filed Sept. 15, 1927 A A K\N mw \hm \NM w h l 3 N Q3 NM; h m wmw wn wn imwi v N 6 H m M V N V Z u O N! NU *0 WW q kn nmw mw aw mN M N W i w M M a N MNI July 2, 1929. ERNST 1.719.593

VARIABLE DISPLACEMENT PUMP Filed Sept. 15, 1927 I5 Sheets-Sheet 2 Gumm July 2, 1929. ERNST 111 91593 VARIABLE DISPLACEMENT PUMP Filed Sept. 15, 1927 3 Sheets-Sheet 5 IKE 4% 4 F a 1% f2 70% P W gvwemboz mama July 2, 1929.

UNITED STATES it i 1,719,693

PATENT OFFICE.

ms imns'r, or cmcnnm'rrfomo. ASSIGNOB To his cmcnma'rr alumna, m.

cm conumv, or CINCINNATI, orno, A conronxnon or one.

VABIABLE-DISPLACEHENT Pm.

. Application fled September s, 1927. Serial in.

This inventiondeals with hydraulics and it relates more particularly. to a new and improved hydraulic pump mechanism of the variable displacement type. I

I Herctofore, variable displacement pumps have been provided, in which reciprocating pistons, moving in opposite dlrectlons in a single cylinder, or intwo connected cyl nders,'act, first, upon retraction, to effect 111- take of fluid and then, upon advance to expel the fluid previously taken in. These pistons usuallyhave been actuated by swash plates, tilting-boxes or cams and the effective action of the pump has been regulated and 16 controlled'by varying the angularityof the piston actuating means, thereby varymg the extent of movementof the pistons; These rior devices present structural and operat-f' mg difliculties which this nvention aims to- 20 eliminate. n

One of the objects of the present invention is to provide an improved variable displacement pump embodying oneor more pairs of pistons reciprocating in oppositlon and to 2 provide improved actuating means for said pistons, whereby pump displacement readily may be varied without varymg the extent of movement of said pistons. More specifically stated, an object of this invention is to provide, in a variable dis lacement pump, separate actuating means or each of the two op posed pistons, each of said actuating means having a constant and predetermined action upon its related piston, and to provide means for varying the timing of said two actuating means thereby to varythe effective action of said pistons without varying the length of their strokes.

These objects have been attained by the 40 present invention in the employment of two rotating eccentric devices each adapted to actuate one of thetwo pistons of eachpair and by providing means for varying the phase relation of the two eccentrics, whereby the effective strokes of the two pistons of each pair may be varied. With the phase.

angle of the eccentrics at zero the two pistons are given their intake and exhaust strokes simultaneously and synchronously and pump displacement is at maximum. When the phase angle-is at 180 degrees one piston is given its intake stroke while the other is given its exhaust Stroke. thereby effecting a complete compensating action between the two and reducing pump delivery to zero. At

' velocity is, at any instant, equal to the algebraic sum of the instantaneous discharge velocities of the two pistons working cono ntly. Thus by varying the hase angle of the two eccentrics the disp acement of the pump may be varied from zero to maximum,

- In accordance with this invention the two eccentrics arerotatably supported about a common drive shaft and gear trains, actuated by said shaft, rotate said eccentrics syn- I cironously with the shaft. Means, independent of the drive shaft, also is provided for. sinullta-neously adjusting said eccentrics about the axis of said shaft, in opposite directions, thereby to vary the phase relation of the two eccentrics.

piston lmder the influence of the constant pressure. This has been attained by combming in a single pump unit, a constant dehvery high pressure. pump adapted to have its exhaust port connected to the intake end of a hydraulic feed cylinder and a variable displacement pump adapted to have its intake port connected with the exhaust end of the cylinder whereby the variable pump serves as a metering device to regulate'volumetrically the rate at which fluid is ex hausted from the cylinder and consequently the rate at which the piston may move therein under the influence of the constant 95 delivery. pump.

In certain variable displacement pumps heretofore provided intake and exhaust of the fluid has been controlled by bodily roplications and difliculties which add materially to the cost of construction and opli eration. This invention proposes a sim 11c fiod structure which obviates the necessit of rotating the cylinder blocks and in whic the intake and exhaust ports alternately are connected with the pump cylinders without the employment of any additional parts as valve mechanism. This has been attained by so constructing the constant delivery pump and so combining 1t with the variable displacement pump that the former in its normal operation serves as a control valve mechanism for the latter.

A still further object of this invention is to combine with the constant delivery high pressure pump and the variable delivery metering pump a constant delivery low pressure pump of large capacity which conveniently may be use to effect rapid translation of the piston in the feed cylinder. When the improved pump is used in connection with machine tools the rapid translation may be utilized quickly to effect relative movement between a tool and a work. piece to bring the two into working pos1- tion and the slow movement, under t e control of the metering device, may be utilized to effect a feeding movement of the work (or tool) during a machining operation.

Another object of the invention is to rovide in a single pump structure the t ree above mentioned pumps and so to arrange and combine them that they all may be actuated directly from a single rotary shaf journaled in the pump casing.

Other objects and advantages will be in part indicated in the following description and in part rendered apparent therefrom in connection with the annexed drawings.

To enable others skilled in. the art so fully to-apprehend the underlying features hereof that they may embody the same in the various ways contemplated by this invention, drawings depicting a preferred typical construction have been annexed as a part of this disclosure and, in such drawings, like characters of reference denote corresponding parts throughout all the views, of which:-

Figure 1 is a central longitudinal section through a pump apparatus embodying the present invention. Fig. 2 is a section on the line 2.-2 of Fig. 1. Fig. 3 is a section substantially on the line 3-3 of Fig. 1, certain of the parts being broken away to expose underlying elements, better to illustrate the invention. Fig. 4 is a detail section showing the means for adjusting certing journal plates later to be referred to. Fig. 5 is a diagrammatic figure illustrating one practical use of the improved multiple pump.

Referring more particularly to the drawings, the invention is illustrated as embodied in a pump mechanism comprising a casing including a body member A and end plates B and C. This casing forms a support and housing for the variable displacement pump desi nated generally as S, and a constant disp acement high pressure pump H, both later to be described. To the plate B is secured a sub-casing D within which is housed a constant delivery low pressure pump of lar e capacity, designated generally as G and which preferably consists of two intermeshing gears, a and b as is well understood. Within the casing member A there is rotatably supported a drive shaft E, driven as by means of a pulley F secured thereto. This shaft preferabl is journaled in anti-friction bearings 1 an 2 supported by the plates B and C and a similar aring 3 supported by bearing plate a: proxided by the sub-casing.

The body member A constitutes a cylinder block within which is formed one or more pairs of complemental cylinder bores c and d. Preferably these pairs of cylinder bores will be about five in number and will radiate from the axis of the shaft E as shown in Fig. 2. His to be understood however that the invention is not limited to a pump embodying a plurality of pairs of cylinders but that it is equally well adapted to operate with but a sin 1e pair of cylinders. One end of each 0% the cylinders is closed, as for example by cap screws 4 threaded into the outer ends thereof. The inner ends of the cylinders are open and terminate in a relatively large central bore or chamber 5 formed in the member A. The cylinders c and d have their outer ends connected by a port 6 which also communicates with a combined valve and pump chamber 7 later to be referred to. Within the cylinders c and d are slidingly fitted pistons e and f havin their inner ends extending into the cham er 5 where they are engaged by eccentric devices 8 and 9, respectively, supported by and rotated indirectl from the shaft E, as later will be describ The eccentric devices 8 and 9 each may be a unitary structure but preferably they will be formed as shown in the drawings i. e. in two parts of which one is the eccentric proper and the other is a wear ring surrounding the eccentric. The eccentric device 8 is formed with a hub 8 rotatably mounted on the drive shaft E, and formed at one end with a gear 10. Upon the hub 8 is rotatably journaled the hub 9 of the eccentric device 9 which also is rovided with a gear 11. Keyed to the shaft E, adjacent the bearing 2, is a drive gear 12 which serves as the initial gear of a transmission for r0- tating the gears 10 and 11, and thereby their respective eccentric devices, synchronously with the drive shaft. Within the member A there is rotatably journaled, as by means of an anti-friction bearing 13, an internal gear 14, of substantial width. Rotary motion is transmitted to this gear from the gear 12 1,71e,eea

shaft substantially asshown in Fig. 3. In

Fig. 1 the gear 18 is shown in a position which it does not occup ,better to set .forth' the driving connection tween the internal gear 14 and the gear 11.

From the foregoing it will be perceived that rotation of the shaft E will, through the gears mentioned, efiect rotation of the eccentric devices 8 and ,9 synchronously with, and in the samedirection as, the shaft, thereby successively forcing outwardly the various pistons e and f. Retraction of the pistons. may be effected by any suitable means and in the construction illustrated fluid pressure .is utilized for this pur ose as later will be explained. It will be un erstood that when the eccentric devicesare adjusted to coincide, their phase angle will be at zero and therefore the pistons e and f will be given their intake and exhaust strokes simultaneously, thereby efiecting maximum pump displacement. Should the eccentric devices be adjusted relatively about the shaft E 180 degrees, one .piston' will move outwardly to exhaust the fluid from its cylinder simultaneously with the inward or intake movement of the other, thereby roducing a compensating action between t e connected cylinders c and d and reducing pump displacement to zero. Thus it will be seen that pump displacement may be varied to any degree between zero and maximum by varying the phase relation of the two eccentrics 8 and 9.

To provide for this angular adjustment of the eccentrics, the journal plates 21 and 22, which support the intermediate gears 17 and 18, are mounted for angular adjustment in opposite directions about the shaft E. a The plates 21 and 22 are provided with gear sectors 21' and 22- (see Figs. 3 and 4), in the nature of opposed racks, with which are meshed gear elements 23 and 24 fixed upon a manually rotatable shaft 25, journaled in the end plates C, and provided with a hand lever 26 (see Fig. 1). For thesake of compactness the gear elements 23 and 24 may be formed on diametrically opposite sides of a single blank but it'is to be understood that independent elementsv may be provided if desired' The shaft 25 projects through a clearance slot 26 formed in the plate 21, which slot permits of adjustment of the plate.

Refcrringnow to. Fig. 3, in which the parts are shown in their intermediate pus-i- 1 tion, thus placing the phase angle of the eccentrics 8 and9 at an angle of 90 degrees,

(which. causes the variable displacement pump to be substantially fifty per cent ef-,

feetive) it will be observed that rotation of the shaft 25 and gear elements 23 and 24 clockwise will cause the p 21 also to be moved clockwise." At the same time the plate 22 will be moved counter clockwise the same extent; Due to the fact that the gears 17 'and 18, carried by ,said

journal plate journal plates both mesh with the internal gear 14 and each tends to turn the gear in the direction of movement of its journal plate the internal gear will be maintained stationary and the resultant. action will be counter-clockwise rotation of the gear 17 and clockwise rotation'of the gear 18. This rotation is reversed in the gears 10 andlll and the eccentrics 8 and 9 will each be moved 45 degrees in opposite directions about the axis of the shaft E causing the eccentrics to coincide, -or in other words to reduce the phase angle to zero,thereby effecting maximum pump displacement.- Likewise when the shaft 25 is rotated counter-clockwise from the position shown in Fig. 3 the plates, gears and eccentrics will be'moved in the reverse direction and the phase angle of the eccentrics 8 and 9 j will be changed from 90 degrees to 180 degrees thereby bringing pump displace ment tozero, as hereinbefore explained.

The end plate B of the pump casing is provided with an intake'chamber or port 28 and an exhaust chamber or port 27 (see Fig.

1) of which the former (when the device is used as a conventional variable displacement pump) may be connected with any suitable fluid supply, and the latter may be hydraulij cally connected with any mechanism to which fluid is to be delivered or to any point l where work is to be performed. When the variable displacement pump is used as a met'ering device, as hereinbefore explained, the intake port 28 is connected with the exhaust end of the feed cylinder. These intake and exhaust chambers are of annular form and are connected alternately with the various pairs of cylinders c and at through the action of reciprocating pistons 29 movable in bores forme in the casing member A. These pistons perform dual functions. Primarily they serve as piston elements of a constant delivery high pressure pumpH, later to be described, and secondarily they serve as control valves for the variable displacement pump S. Their function as control valves or the variable displacement or metering pump will first-be explained. Each of the valve mechanisms (there being one for each.

air of cylinders) comprises a cylindrical ore 7, formed in the casing member A, and

l ev

a reciprocating plunger or piston 29 fitted within said bore. Ports 31 and 30 connect the intake and exhaust chambers, respectively with the bore 7. The. combined valve and pump pistons 29 are each formed with enlarged portions 29" and 29 WlllCll fit within the bore 7, and an intermediate reduced portion 29 providing a fluid passage which, when the piston is in its innermost position connects the ort 31 with the port 6, thereby permitting the pistons e and f durmg retraction to draw in fluid from the intake port 28. When the valve piston is in its outermost position the portion 29 connects the port 6 with the exhaust chamber 27 and simultaneous outward movement of the pistons e and f exhausts therethrough the fluid from the cylinders c and d. From the annular chamber 27 the ejected fluid flows through a duct to a control valve K later'to be referred to. A ball check valve 40 in the duct 40 prevents reverse flow therethrough.

Reciprocator motion is given to the combined valve an pump piston 29 by means of an eccentric element 32, fixed to the drive shaft E, which acts upon the inwardly projecting end 29 of the piston. Any suitable means may be provided for forcing the valve member 29 inwardly to maintain its end in contact with the eccentric but preferably this will be accomplished by-fluid pressure. The

' phase angle of the valve actuating eccentric is initially arranged at 90 degrees from the phase angle of the eccentrics 8 and 9 when in coincidence and inasmuch as the latter eccentrics are adjustable equal amounts in 01pposite direction about the drive shaft t phase of the eccentric 32 willbe maintained at that angle to the combined phases of the eccentrics 8 and 9, thereby causing movement of the valve piston in timed relation with the movement of the pump pistons l and f to effect-a pumping action.

From the foregoing it will be perceived that rotation of the shaft E, and the eccentric 32 thereon, will effectcontinuous reci rocation of the plungers 29 in the bores As hereinbefore stated these plungers also act as pumps and the reciprocatory motions thereof effect the intake of fluid to and exhaust of fluid from the bore 7, which serves as the pump cylinder, As shown in Fig. 1 the piston 29 is formedwith a central bore 37 which terminates adjacent the lower end of the piston and is connected by a transverse duct 37 with a reduced annular portion 29 of the piston. This reduced portion is maintained constantly in communication with a port 36 connected with an annular chamber 35 formed in the end plate B. This chamber is maintained filled with fluid under pressure, said fluid entering the chamber 35 through a duct 34 connected with the exhaust end of the constantly running gear pump G. The outer end of the bore 37 in the -piston 29 is normally closed by a ball check of the piston, the fluid under pressure from the gear pump passes the check valve 41 and enters the upper or outer end of the bore 7, which may be closed in any suitable manner such for example as by a screw 42. Fluid under pressure which passes the check valve 41 acts upon the outer end of the piston and forces it inwardly and maintains its inner end 29 in engagement with the eccentric 32. Outward movement of the plunger 29, under the influence of the eccentric 32 causes the fluid in the outer end of the cylinder 7 to be expelled through a port 43, past a ball check valve 38, and through a duct 39 which communicates with the exhaust port 40 of the variable displacement pump. Thus it will be seen that although the pumps S and H have different sources of supply their exhausts may be combined. It is to be understood however that this combining. of the exhausts is not essential to a proper functioning of either or both of the pumps.

, As hereinbefore stated this invention also contemplates combining a constantly acting gear pump with the variable displacement pump S and the constant delivery pump H above described. Fig. 5 represents diagrammaticall one use to which a combination pump 0 this nature advantageously may be put. In that figure T represents the table of a machine tool, W the work thereon and X a cutting tool adapted, upon movement of the table T to the left, to operate upon the work. The table is adapted to be moved hydraulically as by means of fluid ressure admitted into a cylinder Y at one side of a piston P, suitably connected with the work table. In certain types of machine tools it is highly desirable that the rate offeed stroke and that the work table be prevented from jumping ahead either through the action of the feed mechanism or by the action of the tool on the work. The present multiple pump is well adapted to effect this constant feed and to prevent jumping of the work table and also to efi'ect rapid traverse of the table. The gear pump G, of which the drive gear a is secured to the shaft E, is adapted constantly to draw liquid from a suitable reservoir R, through an intake 2' and exhaust it through an exhaust port j, which latter is, at certain times, through the manipulation of suitable valves, connected with one end of the cylinder Y, the opposite end of the cylinder then being connected with the reservoir whereupon sub stantially the entire output of the gear pump is transmitted to the cylinder and cylinder,

rapid movement of the piston P therein and eonse uently rapid traverse of the work table is c ected.

When it is desired to, effect slow feeding movement of the table'as for example to the left in Fig. 5, pump G is rendered ineffective, by connecting 1ts exhaust end back to the reservoir, as shown by arrows t in Fig. 5, whereupon the pump may continue to rotate without effecting movement of the piston P- The high pressure constant delivery pump H is then connected to the right end of the cylinder Y, as indicated by arrows p, .and transmits thereinto fluid under pressure which tends to shift the piston to the left.

It will readily be perceived that inasmuch as the opposite end of the cylinder Y also is filled with fluid, the rate of movement of the piston P will be determined by the rate at which the fluid is exhausted from the left end of the cylinder. To compensate for the variation between the rate of delivery'of the pump H and the rate at which fluid is exhausted fromthe cylinder Y a relief line, controlled by a relief valve V, is connected with the exhaust port of the pump H. This relief line extends back to the reservoir R and maintains a constant pressure in the intake end of the cylinder. The variable displacement pump S hereinbefore described is now connected with the left end of the cylinder, as indicated by arrows 'v and acts to withdraw, from the measured amounts of fluid, thereby determining volumetrically the rate at which the work table may move under the influence of the high pressure pump, which rate may be varied by varying the action of the pump S but which may not be increased by any amount of pressure in the right end of the cylinder. able displacement pump may exhaust back into the reservoir R as shown in dotted lines 121. in Fig. 5 but preferabl it will exhaust into the exhaust line of t e high pressure pump H, as shown in Fig. 1 and in full lines in Fig. 5. By so connecting the exhaust ends of the two pumps a much lower capacity constant delivery pump may be utilized to maintain the predetermined pressure in the cylinder.

The gear pump G also serves to transmit fluid under pressure through a port 33 into a chamber 33 from which it flows through duct 34 into the high pressure pump H as 'hereinbefore stated.

Valves, designated generally as L and K, serve to control and stop the movement of the mechanism actuated by the improved pump, but inasmuch as the articular construction and operation these valves forms no part of the resent invention, detailed illustration and description thereof is deemed unnecessary in this application.

The vari- For a complete-understanding of the construction and function of these valves reference may be. had to assignees copending applications Serial No. 128,167 filed Au ust 9, 1926, and Serial No. 220,721 'filed September 15, 1927. r

Throughout this specification I have referred to pairs of ump cylinders and a plston in each cylin er. It is to be understood, however, that this invention is not limited to that specific construction but is also adaptable to a pump in which two pistons operate in a single cylinder, which in effect is a pair of cylinders placed end to end, and the claims areto be construed to cover the latter construction.

Without further analysis, the foregoing will so fully reveal the '1st of this invention that others can, by app edge, readily adapt it for-various utilizations b retaining one or more of the features that, rom the standpoint of the prior art, fairly constitute essential characteristics of either the generic or specific aspects of this invention, and, therefore, such adaptations should be, andare' intended to be, comprehended within the meaning and range of equivalency of the following claims.

Having-thus revealed this invention, I claim as new and desire to secure the following combinations and elements, or equivalents thereof, by Letters Patent of the United States 1. A pump combining a casing providing an intake port, an exhaust port and a pair of connected cylinders; a rotary shaft journalcd in said casing; a piston'within each of said cylinders; a pair of eccentric devices actuated by said shaft, each of said eccentric devices being adapted to actuate one of said pistons; a valve mechanism'within said casing, said valve mechanism acting successively to connect said cylinders simultaneously with said intake and exhaust ports; and a third eccentric device actuated by said shaft to shift said valve mechanism.

2. A pumpcombining a casing providing intake and exhaust ports; a rotary shaft journaled in said casing; a plurality of pairs of connected c linders; a piston reciprocable within each of said cylinders; a pair of eccentric devices actuated by said shaft, each of said eccentric devices being adapted to actuate one of the pistons of each pair; an individual valve'mechanism connected with said intake and exhaust ports for simultaying current knowl-' neously controlling the flow of fluid to and from each pair of cylinders; and an eccentric device actuated by said shaft for shifting all of said valve mechanisms.

8. A pump combining a casing providing intake and exhaust ports; a rotary shaft journaled in said casing; a pair of connected cylinders; means simultaneously to connect said cylinders alternately with said intake and exhaust ports; a piston reciprocable within each of said cylinders; two constantthrow eccentric devices carried by said shaft and each adapted to actuate one of said pistons; means to adjust said eccentric devices an larly about the axis of said shaft selective y to produce opposed reciprocations of said pistons thereby to effect a pump1ng action and also to effect compensatlng movements of said pistons to render said pump ineffective.

4. A pump combining a casing providing intake and exhaust ports; a pair of connected cylinders; a piston reciprocable within each of said cylinders; means to connect said cylinders alternately with said intake and exhaust ports; a pair of rotatableeccentric devices within said casing each adapted to reciprocate one of said pistons; and means operative during rotation of said eccentric devices, to vary their phase relation, thereby to vary pump displacement.

5. A pump combining a casing providing intake and exhaust ports; a pair of connected cylinders; a piston reciprocable within each of said cylinders; valve mechanism adapted to connect said cylinders alternately with said intake and exhaust ports; three co-axially mounted rotary eccentric devices, of which one is adapted to actuate said valve mechanism and of which two each actuate one of said pistons; and means operative during rotation of said eccentric devices simultaneously to shift said two eccentric devices relative to each other and relative to the first named eccentric device, thereby to vary the phase relation between said two eccentrics to vary pump displacement without varying the actuation of said valve.

6. A pump combining a casing providing intake and exhaust ports; a pair of connected cylinders; a piston reciprocable within each of said cylinders; valve mechanism adapted to connect said cylinders alternately with said intake and exhaust ports; a rotary eccentric device for actuating said valve mechanism in timed relation with the reciprocation of said pistons; a rotary eccentric device acting upon each of said pistons to give them opposed reciprocations to effect maximum pump displacement, said valve and piston actuating eccentrics being so arranged that the phase of the former is maintained at a predetermined angle to the combined phases of the latter; and means for shifting said piston actuating eccentrics in opposite directions about a common axis to vary their phase relation thereby to re-. duce pump displacement.

7. pump combining a casing provided with intake and exhaust ports; a rotary shaft journaled in said casing; a plurality of radially arranged pairs of connected cylinders; a piston reciprocable within each of said cylinders; a valve device co-operating with each of said pairs of cylinders and adapted to connect its associated pair of cylinders alternately with said intake and exhaust orts; an eccentric device fixed to said sha t for actuating said valve mechanism; two eccentric devices supported by said shaft for reciprocating said pistons; a gear journaled in said casing; a driving connection between said shaft and said ear to rotate the latter; and an indepen ent driving connection between said gear and each of the piston actuating eccentrics.

8. A pump combining a casing provided with intake and exhaust ports; a rotary shaft journaled in said casing; a pair of parallel cylinders connected together by a duct; a reciprocating plunger valve adapted to connect said duct alternately with said intake and exhaust ports; an eccentric secured to said shaft and adapted to shift said plun er valve; two eccentrics supported by said s aft and each adapted to reciprocate one of said pistons; means actuated by said shaft to rotate said two eccentrics synchronously with said shaft, said two eccentrics being arranged with their phase angle at zero for maximum pump displacement; and means to adjust said two eccentrics angularly about the axis of said shaft in opposite directions to vary their phase relation, thereby tovary pump displacement.

9. A pump combining a pair of connected cylinders; a piston reciprocable in each of said cylinders; a rotating shaft journaled in said casing; a first gear fixed to said shaft; an internal second gear journaled in said casing; an intermediate third gear j ournaled in said casing and affording a driving connection between the first and second gears; a fourth gear rotatably journaled on said shaft and provided with a hub; an eccentric element rotatable with said hub; a fifth gear rotatably mounted on said hub; a second eccentric element rotatable with the last named gear; said eccentric elements being adapted to give to said pistons opposed reciprocations; driving connections between said internal gear and said fourth and fifth gears; and means to vary the phase relation of said eccentrics to vary pump delivery.

10. A pump combining a casing provided with intake and exhaust ports; a pair of connected cylinders; apiston reciprocable in each of said cylinders; a valve actuated in timed relation with the movement of said pistons to connect said cylinders alternately with said intake and exhaust ports; means to reciprocate said pistons to cause them simultaneously to effect intake strokes while said cylinders are connected with said intake port and simultaneously to effect exhaust strokes while said cylinders are connected with the exhaust port, thereby to.

produce maximum pump delivery; and

' a compensating action therebetween tovary the rate of pump delivery, the discharge velocity being equal at any instant to the algebraic sum of instantaneous discharge of g the two pistons working .in conjunction.

11. A pump combining a pair of connected cylinders; a piston reciprocable in each cylinder; a rotating shaft and a ar journaled in said casing; means actuaterfl: said shaft to rotate said gear; two journa plates adjustably mounted within said casing; two pistons actuating eccentric elements rotatably supported by said shaft; a gear connected with each of said eccentric elements; an intermediate gear journaled upon each of said journal plates and each affording a driving connection between the first named gear and one of the gears on said eccentrics thereby to rotate said eccentrics synchronously; and means to adjust said 'ournal plates in op osite directions about t e axis of said sha t to'vary the phase relation of said eccentrics to vary the timing of reciprocation of said pistons and thereby the extent of their compensating action.

12. A ump as set forth in claim 11 in which ad ustment of the journal plates, and thereby angular ad'ustment of said eccentric elements, is efiecte by gear sectors on said journal plates and manually rotatable gear elements in mesh with said gear sectors.

v13. A ump as set forth in claim 11 in which ad ustment of the journal plates, and thereby angularadjustment of said eccentric elements in opposite directions, is effected by internal and external gear sectors on said journal plates; a shaft journaled in said casing; a gear element secured to said shaft and meshing with said gear sectors; and manual means to rotate said shaft.

14. A pump combining a plurality of radially arranged sets of parallel cylinder bores, each of said sets comprising a pair of connected ump cylinders and a valve cylinder; a piston reciprocable in each of said pump cylinders; a valve member in the other of said cylinders, adapted to connect said pump cylinders alternately with intake and exhaust ports; a rotatable shaft journaled in said casing; three eccentric elements supportedby said shaft and rotatable synchronously therewith, one of said eccentric elements acting to shift said valve member and the other twoeach arranged to reciprocate one of said pistons, the valve actuating eccentric being arranged with its phase angle at substantially 90 degrees from the combined phase of said piston reciprocating eccentrics; and means to vary the phase angle of the last named eccentrics from zero to 180 degrees, to vary the movements of said pistons from directly opposed movements effecting maximum delivery to com-' pletely com ensating movements to negative pump elivery.

A variable dis lacement pump comblnlng a casing provi( ing intake and exhaust ports; a rotary shaft, a pair of connected cylinders; means to connect said cylinders a ternately w1th said intake and exhaust ports; a piston reciprocable in each of said cylinders; a pair of eccentric elements rotatable with said shaft and adapted simultaneously to give to said pistons exhaust movements; and means to vary the phase relation of said eccentrics.

16. A variable'displacement pump combining a stationary cylinder block provided with a plurality of pairs of radially extendmg cylinders having their inner ends open; a rotary shaft extending through said cylinder block; complemental pistons reciprocable in each pair of said cylinders and proecting from their'inner ends; annular intake and exhaust ports common to all of said cylinders; independent valve means associated with each of said pairs of cylinders and adapted to connect them alternately with said intake and exhaust ports; an eccentric device secured to said shaft and adapted upon a complete rotation to actuate all of said valve means; two eccentric elements 'rotatable synchronously withsaid shaft and each adapted to engage the inner ends of and to actuate oneof each pair of pistons; and means to vary the phase relation of said eccentric elements.

17. A fluid delivery apparatus combining a variable delivery pump including a pair of connected cylinders, pistons reciprocable in said cylinders, anintake chamber for supplying fluid to said cylinders, an exhaust chamber for receiving the fluid expelled from said cylinders, a reciprocating valve member for simultaneously connecting the cylinders alternately with the intake and exhaust chamber in timed relation with the movement of said pistons; a cylinder within which the valve member is slidingly fitted,-

a fluid intake portconnected with one end of the last mentioned cylinder for admitting fluid thereunto; an exhaust port connected with the last mentioned cylinder; check valves for closing the last mentioned intake and exhaust ports; and means to reciprocate said valve member to cause it to control the intake and exhaust of said variable delivery pump and simultaneously therewith to effectan invariable pumping action through the second-mentioned intake and exhaust ports.

18. A fluid delivery apparatus comprising a unitary structure combining a casing; a power shaft journaled therein; a variable delivery pump embodied in said casing and including a pair of connected cylinders and a pair of pistons reciprocable in said cylinders; eccentric elements actuated by said. shaft for reciprocating said pistons; intake and exhaust chambers adapted alternately to be connected with said cylinders in timed relation with the movement of said pistons; a constant delivery pump embodied in said casing, the last named pump including 2. cylinder, intake and exhaust ports connected therewith and a reciprocating piston which also serves as a valve to control the inlet and outlet of the variable delivery pump.

19. A fluid delivery apparatus combining a casing; a variable displacement pump within said. casing, said pump comprisinga pair; of connected cylinders, an intake and an exhaust port common to'both of said cylinders; a pair of pistons reciprocable in said cylinders; means to vary the time of reciprocation of said pistons relative to each othor to vary pump displacement; a third cylinder; a combined pump piston and control valve reciprocable in said third cylinder; means to give the combined piston and valve element reciprocatory movements in timed relation with the movement of the pistons of the variable pump to effect a pumping action and to control the intake and exhaust of the variable pump; intake and exhaust ports connected with said third cylinder, the exhaust port of the variable pump and the last named exhaust port being connected to combine the delivery of the two pumps.

20. A fluid delivery apparatus combining a variable delivery pump including pump cylinders, pistons reciprocable in said cylinders and intake and exhaust ports for admitting fluid into and out of said cylinders; a constant delivery pump including a cylinder; intake and exhaust ports connected with said cylinder; and a piston reciprocating in the last named cylinder alternately to effect intake and exhaust of fluid therefrom; means to reciprocate the last named piston in timed relation with the movements of the pistons of the variable pump, the piston of the constant delivery pump also serving, in its reciprocations, to open and close the intake and exhaust ports of the variable delivery pump.

21. A fluid deliverfi apparatus combining a casing; a power s aft journaled in said casing; a variable delivery pump and a constant delivery pump within said casing; means actuated by said power shaft for actuating both of said pumps simultaneously in timed relation, said constant delivery. pump including a reciprocating iston which also serves as a control valve or the variable delivery pump.

exhaust ports adapted to be connected with said cylinders in timed relation with the reciprocation of the pistons; a third cylinder; intake and exhaust ports connected with the third cylinder; a combined pump piston and valve member reciprocable in the third cylinder, said combined member acting in its reciprocations to effect intake and exhaust of fluid into and out ofthe third cylinder and alternately to connect the first mentioned intake and exhaust ports with the pair of connected cylinders; three eccentric devices mounted upon a common actuator each of said eccentric devices serving to transmit re ciprocations of predetermined length to one of said pistons; means for varying the phase relation of two of said eccentrics relative to each other and to the third eccentric, thereby to vary the delivery from the pair of connected cylinders without varying the action orv timing of the combined valve and pump plston.

24:. .A fluid delivery apparatus comprising a unitary structure combining a casin a gear pump and a constant delivery high pressure pump embodied in said casing and each actuated continuously from said shaft the exhaust side of said gear pump being connected with the intake side of sa1d high pressure pump to deliver fluid to the latter under pressure; a variable delivery pump embodied in said casing and actuated from said shaft; means to vary the action of said variable displacement pump without affecting the action of the other two pumps, said constant delivery high pressure pump being arranged to serve as control valve mechanism for the intake and exhaust of the variable delivery pump.

' In witness whereof, I hereunto subscribe my name.

HANS ERNST. 

